Method of producing fibrous threads



Patented rang, It, 1933 trim JOAQUIN JULIO DE LA ROZA, $3., OF BROOKLYN, NEW YORK, ASSIGNOE TO BAG-AS512 PBGDUCTS CGBPORATION, OF NEW" YORK, N. Y., A COREORA'IION OF NEW YORK ItIETHOD OF PRODUCING FIBROUS THBEAD 6 Ho Drawing.

This invention relates to a method of producing fibrous threads from a byproduct of sugar cane commonly known as bagasse, and has for an object to provide for the production of soft, strong, flexible fibrous threads which can be spun, woven, and otherwise generally worked into textiles, bags, cordage, and other analogous articles of commerce.

9 Another object consists in providing certain improvements in the said article and method whereby advantageous results are obtained.

In the manufacture of sugar the cane is crushed between rollers, in a well understood manner, and, as a result of this crushing operation there is left the coarse fibrous element of the sugar cane, which is known as bagasse. This substance is produced in very large quantity and, at present, it is commonly used as tuel for firing the power plants of the sugar factories which operate upon the cane. The material is not very suitable as a fuel, largely because of its low calorific value but, the great amount produced calls for its use in such manner in Gil the absence of a more profitable employment of it. My invention contemplates utilizing the bagasse in a much more profitable manner so that it will be economical to fire the factory furnace with more efficient fuel, such as coal or oil, thereby bettering the manufacturing. operations in this respect, in addition to obtaining the very substantial profit from the novel employment of the bagasse. To illustrate, the fibrous threads produced by my method may be woven into bags for transporting the sugar.

It is my belief that I have devised a method of producing the fibrous threads, above named. in a manner which is comniercially economical and practicable, and which does not impair the native strength of the fibrous element of the sugar cane.

Previous efi'orts to utilize bagasse have consisted mainly in attempts to manufacture paper or heavy board, and have'uniformly embodied, in the main, treating the bagasse to a more or less drastic digestion with ac caustic alkali or other chemicals, and I have Application filed November a, 1926. Serial No. 147,392.

determined that, when the bagasse of sugar cane is subjected to such a digestion treatment, various substances bound in with the bagasse, such as the complex carbohydrates and the like, gelatinize, and the subsequent steps required in the effort to eliminate said gelatinized substances greatly in'ure the native properties of the bagasse fibers which would render them' appropriate for textile operations such as I contemplate and have indicated above.

Various other efi'orts to utilize bagasse for the manufacture of paper pulp, which have. embodied certain treatment previous to digestion, have failed to conduct such treatment under conditions necessary for the attainment of satisfactory results, and have been quite unsuited to the production of the fibrous threads which are obtained through the employment of my present invention.

Analysis of sugar cane reveals the fact that, besides water and sucrose, it contains a number of complex carbo-hydrates of wholly or partially undetermined nature, and also a greater or lesser amount of cellulose and pentosans. Such analysis further discloses that the fibrous portion of the cane retains, in mechanical or chemical combination with the pithor parenchyma, and

together with the cellulose cells, a substani tial part of the water content of the cane,

as well as sucrose, dextrose, levulose, pentosans, (xylan and araban), lignin complexes, and other substances. In either an alkaline or acid treatment, of any substantial intensity, some or all of these substances elatinize and become measurably or hig ly' insoluble. Subsequent treatment accomplishing the removal of such gelatinized complexes, for instance by their destruction, is also accompanied by injury of a greater or lesser degree to the fibers of the cellulose part of the bagasse, the extent of which injury may depend upon the strength of the digesting solution, or the length of time of digestion treatment, or the temperature thereof, or of any two or all of these factors.

Having in mind these previous ditficulties, my invention comprehends a treatment ice of the bagasse or fibrous elements of sugar cane which separates the substances other than the fibrous elements from the latter without injuring the fibrous elements by said treatment and without gelatinizing or otherwise transforming the said substances so as to require for their separation another treatment injuring the fibers.

Broadly speaking, this invention comprehends subjecting the bagasse or fibrous elements of sugar cane to a first treatment with hot water at a temperature of approximately 160 to 178 centigrade, which treatment generates an acid condition resulting from the decomposition of the sugars into organic acids; the utilization of this acid condition for changing the incrusting substances so as to render them readily soluble in dilute alkali as, for instance, by changing xylan and araban into xylose and arabinose; and then the treatment of thematerial with a cold dilute alkali and washing so as to remove the said substances and leave the fibrous threads desired.

My invention thus avoids any intense acid or alkaline treatment, thereby elimimating the disadvantages above described, together With others inherent in such intense treatments. Italso promotes economy and improves the product.

In carrying out my invention, the bagasse is conveyed, by means of blowers or other suitable arrangement, into the interior of a vessel which is preferably substantially like the standard sulphite pulp digestcr. This vessel is preferably composed of ferric material, such as steel or iron, lined with brick adapted to resist the alternating action of dilute acid and dilute alkali. This character of brick is known to the chemical industry although itdifiers sharply from brick used in the standard sulphite pulp digesters in that the latter are specially designed to withstand acid action only. The arrangement of valves, vents and the like may differ to a certain extent from the standard arrangement of the sulphite digesters, but such changes are well within the skill of the calling and merely for the purpose. of better adapting the apparatus to the specific conditions in hand.

After the bagasse has been passed into this vessel, the valves, vents, openings and the like are closed, and water is added. I prefer to use hot water if it can be economically obtained and, indeed, the hotter the water is the more the process will be expedited. After the vessel has been substantially filled with water, steam is injected and the contents heated quite rapidly up to a temperature of approximately centigrade. At this point a vent is openedso as to relieve substantially all of the entrapped air. This vent is then closed, or substantially closed,

.hundred twenty minutes or more.

so that no appreciable amount of water or steam can escape from the interior.

Additional steam is then injected, although somcwhat more slowly than before, until a temperature of from to 173 centigrade is reached.

I may say, at this point, that the matter of temperature is one of substantial importance because the desired action upon the incrusting materials is not at all effective at a temperature substantially less than 160 centigrade. while, at a temperature higher than approximately 173 is liability of a serious injury to the fiber, and the production of so-called caramel and humic compounds. It should also be kept in mind that the temperature cannot certainly be determined from the pressure alone, because pressure indications are apt to be augmented as a result of gas pressure automatically developed during process. Therefore it is important to observe the temperature requirements and to use a thermometer for directly indicating the same.

After the temperature above named has been reached, the charge is allowed to remain, while the temperature is maintained, for a period of from, say, thirty to one This time period depends mainly on the condition, age, etc. of the bagassc. I prefer to use fresh bagasse whenever possible or, at least, bagasse which has not been verv long exposed to conditions leading to rotting or oxidizing. However, the process is adaptable to the use of old, baled bagasse, or wet bagasse or fermented bagasse, or any other form of bagasse that may be encountered in sugar manufacture, without greatly altering the high quality of resulting cellulose fiber. The limitations above named will ordinarily cover the varying characteristics of the material being treated, but, in an extreme case, the time may be extended beyond one hundred twenty minutes, and the determination of this will be within the capacity of the skilled operator in charge.

It is desirable, Whenever possible, to avoid a treatment of over one hundred twenty minutes at the temperature range of 160 to 173 Centigrade because, at such elevated temperature, some of the acids automatically generated will attack and injure the cellulose if the treatment is prolonged. This may result in the bag'asse becoming appreciably dark and having the general appearanee and characteristics of humic compounds, while the fibers may be appreciably weakened. It may be thought that such effects may facilitate the subsequent treat ment with the dilute alkali but, even if this be so, the formation of the humic compounds and the weakening of the fibers has a tendency to offset any such gain and to prejcentigrade, there emon udice the attainment of a fiber of the highest quality. Accordingly, the ideal procedure is one in which this treatment at 160 to 173 centigrade is prolon ed as far as possible without injuring the hber so as, thereby, to facilitate the subsequent dilute alkali treatment, without impairing the quality of the product..

I call this first treatment an acid treatment because it reacts acid (e. g. to litmus) in contrast to the step of subjecting the material to the dilute alkali bath to be hereinafter described, and is one characteristic which sharply distinguishes my process from the older processes in which material for paper pulp has been directly, or without my first treatment, submitted to alkali digestion. U

. This treatment at 160 to 173 centigrade automatically generates an acid condition owing to the decomposition of certain sugars into organic acids and this acid bath directly dissolves some of the incrusting substances and has a hydrolytic action upon others whereby they are changed so as to be readily soluble in dilute alkali. For instance, such inc-rusting substances as xylan and araba are changed into xylose and arabiuose which are readily dissolved by dilute alkali.

A fter the charge has been subjected to this treatment for the determined period of time, the pressure in the vessel is relieved to a certain extent by the opening of a vent, and the acidified liquid, containing such sub stances as may have been dissolved, is allowed to blow from or is otherwise removed from the vessel.

When the acidified ll( aid has been removed, the vessel is re. lled with warm water, and the latter then allowed to drain from the vessel for from fifteen to thirty minutes.

After this water has drained from the vessel, the charge is removed to an open vat or tank, preferably provided with suitable agitating devices, and it is therein washed with cold water, such as ordinary river or rain water; or, in the alternative, the washing may take place in the same vessel by repeated filling and draining.

The charge is thcn removed to an open vessel, which may be composed of iron or steel, suitably lincd to resist the action of bagasse in alkali solution. and a cold solution of dilute alkali is added. This solution should ordinarily not have a tempera ture higher than. about 40 ccntigradc, and it w ll generally be found that atmospheric t mperature is suitable. It may be of a strength equivalent to from two to ten grams of potassium or sodium hydroxide per litre of water. This cold dilute alkali solution is allowed to act upon the charge. with suitable agitation, for a period of from about two to ten hours depending upon conditions and, especially, on the strength of the solution. The greater the strength, the stronger the action and the less time required, but, as there is danger of weakening the fibers if the solution is too strong, I prefer a very dilute solution with several hourstrcatment.

The effect of this cold dilute alkaline bath is to greatly soften the incrusting substances and at the end of this period of treatment the solution is drained or otherwise removed from the vessel. I

The nextstep is to wash the charge once or more with cold water, which may be river or rain water at ordinary atmospheric temperature. This step may be carried out in the same vessel by adding the waterand permitting it to drain therefrom; or the charge may be removed to another regular washing vat, and therein washed in the usual manner while being agitated. I prefer to wash at least two or three times, as a thorough washing more completely cleanses the fibers and assists in eliminating the objectionable incrusting matters. I

After the washing has been completed. the material may be passed through fluted rollers, or combed or carded, or the like, which procedure will remove such incrusting substances as remain after the previous treatments.

The resulting textile fibers may then be thoroughly washed with ordinary water,

after which they can be dried and spun into thread suitable for weaving.

lVhile I have rcferrcd throughout to the employment of bagasse at the outset of my method, it will be understood that I'might start with the sugar cane itself. and separate the fibers as herein set forth. Ordinarily. of course, the bagasse would be the starting material because that is a common by-product obtainable in large volume, but I do not wish to have the application of this invention limited to bagasse as the initial material sincc, as above indicatcd. the cane itself may be employed.

Furthermore, it is a feature of this invention that I may utilize sugar cane. which has been damaged with respect to its adapta- -bility for the manufacture of sugar as. for

instance. by tires in the cane lields. 'Such damaged sugar cane is still suitable for treatmentby my method and the uninjured fibers can be separated and employed as indicatcd;

From the foregoing it will be seen that the process cmbodics a first treatment with dilute acid and a Hll)1- tjlllli treatment with cold dilute alkali. The acid condition of the first treatment is preferably. as prcviously indicated, brought about by the automatic generation of acids during said treatment, but it may, if desired, be supplemented by the original addition of a small amount of acid to the contents of-the vessel,

I or to the water before it is run into the vessel, without departing from the essence of the invention which includes a mild acid treatment followed by a mild cold alkali treatment. Both the. acid and alkaline treatments are'essentially mild and they are arranged so as to have the alkali treatment follow the acid treatment since the latter acts upon many of the incrusting substances to transform them so to enable their ready removal by the former.

lVhen, in the claims, I refer to treating sugar cane, it will be understood that I intend to cover the treatment of sugar cane fiber, in any form. Generally, and under ordinary circumstances, bagasse will be em-' ployed, as pointed out herein above.

It will be understood that various changes may be resorted to in the steps of the process, in the materials used, and in the apparatus without departing from the spirit and scope of my invention, and hence I do not intend to be limited to the details herein set forth except as they may be included in the claims.

What I claim is:

l. A method of treating sugar cane to produce fibrous threads useful in the textile industry, which includes treating'the fibrous part of the cane with a hot dilute acid solution and with a cold dilute alkali solution.

2; A method of treating sugar cane to produce fibrous threads useful in the textile industry, which includes treating the fibrous part of the cane with a dilute acid solution at a temperature of approximately 160 to 173 centigrade and with a dilute alkali solution at a temperature of approximately 40 centigrade.

' '3. A method of treating sugar cane to produce fibrous threads useful in the textile industry, which includes treating the fibrous part. of the cane with a dilute acid solution at a temperature ofapproximately 160 to 173 centigrade and with a dilute alkali solution at a temperature of approximately 40 centigrade, and washing the'cane with water intermediate said acid and alkali treatments. i a

4. A method of treating sugar cane to produce fibrous'threads useful in the textile industry, which includes treating the fibrous part of the cane with a dilute acid solution and with a dilute alkali solution, and mechanicall separating the fibers from the remainin incrusting substances, the said alkali treatment being conducted at a temperature substantially below that of the said acid treatment.

5. A method of treating sugar cane to produce fibrous threads useful in the textile industry, which includes treating the fibrous part of the cane with a hot dilute acid solution and with a cold dilute alkali solution,

and mechanically separating the fibers from the remaining incrusting substances.

6. A method of treating sugar cane to produce fibrous threads useful in the textile industry, which includes treating the fibrous part of the cane with a hot dilute acid solution and with a cold dilute alkali solution, washing the cane, and mechanically separating the fibers from the remaining incrusting substances.

7 A method of treating sugar cane to produce fibrous threads useful in the textile industry. which includes treating the fibrous part of the came with a hot dilute acid solution, washing the cane, treating the cane with a cold dilute alkali solution, washing the cane, and mechanically separating the fibers from the remaining incrust ing substances.

8. A method of treating sugar cane'to produce fibrous threads useful in the textile industry, which includes treating the fibrous part of the cane with a dilute acid solution at a temperature of approximately 160-to 173 centigrade, washing the cane, treating the cane with a dilute alkali solution at a temperature of approximately 40 centigrade, washing the cane, and mechanically separating the fibers from the remaining incrusting substances.

9. A method of treating sugar cane to pro- 2' duce fibrous threads useful in the textile industry, which includes treating the fibrous 173 centl rade washin the cane with warm water, treating the cane with a dilute alkali solution at a temperature of approximately 40 centigrade, washing the cane with cold "water, and mechanically separating the fibers from the remaining incrusting substances.

In testimony, that I claim the foregoing as my invention, I have signed my name this 8th day of November 1926.

JOAQUIN JULIo DE LA ROZA, SR. 

